In an automotive engine, it is necessary to measure the intake air flow rate in order to control the fuel injection amount. A kind of apparatus for measuring the intake air flow rate is a gas flow rate measuring apparatus of the heat generating resistor type. It is desirable for the gas flow rate measuring apparatus of the heat generating resistor type to exhibit a little variation in output signal, namely, a minor temperature-dependent error, even in the eventuality of a temperature change.
In order to minimize the temperature-dependent error is necessary to correct the temperature-dependent error of a gas flow rate detection signal from a gas temperature or board temperature detection signal.
There is a technology disclosed in JP-2007-071889-A that locally improves the resolution using an irregular-interval correction table in order to enhance the minimum requisite resolution. A gas flow rate measuring apparatus of the heat generating resistor type generally includes an arithmetic operation circuit having table data relating to characteristics of air flow rate and air output. The arithmetic operation circuit divides an area of the table data and uses a correction expression of the output characteristics converted for each of the divisional air flow rate regions to calculate an air flow rate. The area division of the table data is configured from a low flow rate region of the air flow rate divided more finely than a high flow rate region. This division makes it possible to improve the low flow rate accuracy without an extreme increase in the number of data of the table.